Definition of Creatine

William C. Shiel Jr., MD, FACP, FACR

Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.

Creatine: A compound the body synthesizes (makes) and then utilizes to store energy. The storage of energy occurs when phosphate molecules are attached to creatine to create creatine phosphate. Creatine phosphate is capable of donating phosphate to ADP in order to make ATP. ATP can then be converted into ADP with release of energy.

Creatine is sold as a dietary supplement and is used by athletes as a "legal steroid" to increase muscle bulk. There has been some concern about the long-term safety of creatine, particularly as to whether it may cause digestive, muscular and cardiovascular problems and possibly raise the risk of cancer.